The effect of single and multiple application of in-office dental bleaching on tooth sensitivity and bleaching efficacy: A randomized controlled clinical trial.

OBJECTIVE

This randomized controlled trial evaluated the effect of single versus multiple applications of two neutral high-concentration hydrogen peroxide gels on tooth sensitivity and color change.

METHODS

Sixty-four participants with upper canines shades A3 -A3.5 were randomly assigned for bleaching to two groups: Opalescence Boost (40 % hydrogen peroxide) and Pola Office Plus (37.5 % hydrogen peroxide). Each material was applied using a split-mouth design, with single- and multiple-application protocols performed across two sessions. Tooth sensitivity was recorded during and post-treatment evaluation using a Visual Analogue Scale (VAS) and a Numerical Rating Scale (NRS). Color changes were evaluated using VITA Easyshade spectrophotometer (ΔEab, ΔE00 and WID) and the Vita Classical shade guide units (SGU) at baseline, 7 days after bleaching, and one-month after bleaching. Data were analyzed using Paired t-tests for the ΔEab, ΔE00 and WID, and Wilcoxon signed-rank tests for sensitivity intensity and ΔSGU. Significance was set at p < 0.05.

RESULTS

Paired comparisons for tooth sensitivity were consistent in 100 % of participants for Pola Office Plus and 93.3 % for Opalescence Boost, with no significant differences in intensity across either scale (p > 0.05). Regarding whitening efficacy, the single-application protocol yielded significantly higher ΔE00 and ΔWID values at 7 days compared to the multiple-application protocol (p < 0.05). However, at one month, these differences were no longer significant for ΔEab, ΔE00 and ΔWID (p > 0.05). No significant differences in ΔSGU were detected between protocols at any time point (p > 0.05).

CONCLUSIONS

Single-application protocols using neutral, high-concentration hydrogen peroxide gels achieved whitening efficacy and tooth sensitivity outcomes comparable to traditional multiple-application protocols.

CLINICAL SIGNIFICANCE: For neutral in-office bleaching, a single-application protocol provides whitening efficacy and tooth sensitivity outcomes comparable to traditional multiple-application protocols. This simplified approach maintains aesthetic effectiveness while improving chair-side efficiency and reducing material consumption. This clinical trial was registered at ClinicalTrials.gov; the registration number is NCT07173296.